The invention relates to a system for cleaning the surfaces of objects of great surface area with a granular sandblasting agent, having a mobile aerial bucket which can be moved parallel to the surface of the object, in accordance with the generic part of claim 1.
Such a system is disclosed in DE-PS 29 04 093. The known system serves for cleaning and sandblasting, especially of objects of great surface area, such as ships' hulls in a drydock and the like, and it is equipped with an aerial bucket which is movable relative to the work surface of the object. The bucket, for example, is one that is carried on the end of a telescoping boom and has fixedly installed sandblasting nozzles, and it is moved along the ship's hull. At the same time a system is preferably provided for cleaning the sandblasting agent in the bucket itself. It is also known, however, to carry used sandblasting agent and the debris removed thereby away from the bucket into a system for processing them. The sandblasting bucket is guided by means of a digital control unit set up on the side.
Also known are sandblasting systems in which an operator runs a sandblasting apparatus from a shielded pulpit (EP-OS 123 847). However, this sandblasting is performed within a closed work chamber with the corresponding recovery systems. Here the operator is protected, yet dust and dirt particles fly about within the closed work chamber, so that poor visibility prevails therein. Also, the movement of the sandblast guidance system relative to the object is comparatively limited. On account of the requirement that the work be performed inside of the enclosed work area, only those workpieces or objects can be sandblasted therein which can fit within the dimensions of the small amount of space available within the work area. For objects of large surface area, such as ships or aircraft, the known apparatus is unsuitable precisely for this reason and would be in any case uneconomical and too complicated.
The invention is addressed to the problem of devising an apparatus for the cleaning and sandblasting of objects of especially great surface area, such as large space aircraft not contained in an enclosed work area, with a work bucket that can be moved relative to the work surface of the object. Such an apparatus must permit individual observation and guidance by an operator without hampering the movement of the sandblasting head. At the same time, allowance is to be made for the fact that the sandblasting of the outer surfaces of aircraft, especially large space aircraft, is based on a comparatively new technical development. The outcome of this development is that special sandblasting agents made from comparatively hard plastic particles are available, which are capable of economically removing aged and pitted protective coatings from the aircraft's external surfaces which are usually made of aluminum, without attacking the underlying metal. On account of the varied contours of the surface it is advantageous for the progress of the work to be observed and carefully controlled by an operator.
The art of sandblasting aircraft surfaces with plastic grits is basically known. It advantageously eliminates the removal of paint with toxic acids. Employing it in an open hangar, however, is very complicated on account of the flying dust it creates and the difficulty of recovering the grits that have settled on the ground by means of large, special vacuum cleaners, and therefore it is in need of improvement.
Consequently the invention is addressed to the special problem of developing a sandblasting apparatus which will be especially suited for cleaning large areas of aircraft with special nonabrasive grits, and, while avoiding the raising of dust and the escape of particles into the hangar, will permit direct observation of the sandblasted surface by an operator without hampering the freedom of movement and hence the performance of the apparatus.